Source file result.ml

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(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
(* Copyright (c) 2020 Nomadic Labs <contact@nomadic-labs.com>                *)
(*                                                                           *)
(* Permission is hereby granted, free of charge, to any person obtaining a   *)
(* copy of this software and associated documentation files (the "Software"),*)
(* to deal in the Software without restriction, including without limitation *)
(* the rights to use, copy, modify, merge, publish, distribute, sublicense,  *)
(* and/or sell copies of the Software, and to permit persons to whom the     *)
(* Software is furnished to do so, subject to the following conditions:      *)
(*                                                                           *)
(* The above copyright notice and this permission notice shall be included   *)
(* in all copies or substantial portions of the Software.                    *)
(*                                                                           *)
(* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR*)
(* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  *)
(* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL   *)
(* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER*)
(* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING   *)
(* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER       *)
(* DEALINGS IN THE SOFTWARE.                                                 *)
(*                                                                           *)
(*****************************************************************************)

(** A replacement for {!Stdlib.Result} which
    - is exception-safe,
    - includes Lwt-, result-, and Lwt-result-aware traversors.

    See {!Lwtreslib} and {!Seq} for general description of traversors and the
    meaning of [_s], [_e], and [_es] suffixes. *)
module type S = sig
  type ('a, 'e) t = ('a, 'e) result = Ok of 'a | Error of 'e (***)

  val ok : 'a -> ('a, 'e) result

  val ok_s : 'a -> ('a, 'e) result Lwt.t

  val error : 'e -> ('a, 'e) result

  val error_s : 'e -> ('a, 'e) result Lwt.t

  val value : ('a, 'e) result -> default:'a -> 'a

  val value_f : ('a, 'e) result -> default:(unit -> 'a) -> 'a

  val bind : ('a, 'e) result -> ('a -> ('b, 'e) result) -> ('b, 'e) result

  val bind_s :
    ('a, 'e) result -> ('a -> ('b, 'e) result Lwt.t) -> ('b, 'e) result Lwt.t

  val bind_error : ('a, 'e) result -> ('e -> ('a, 'f) result) -> ('a, 'f) result

  val bind_error_s :
    ('a, 'e) result -> ('e -> ('a, 'f) result Lwt.t) -> ('a, 'f) result Lwt.t

  val join : (('a, 'e) result, 'e) result -> ('a, 'e) result

  val map : ('a -> 'b) -> ('a, 'e) result -> ('b, 'e) result

  (* NOTE: [map_e] is [bind] *)
  val map_e : ('a -> ('b, 'e) result) -> ('a, 'e) result -> ('b, 'e) result

  val map_s : ('a -> 'b Lwt.t) -> ('a, 'e) result -> ('b, 'e) result Lwt.t

  (* NOTE: [map_es] is [bind_s] *)
  val map_es :
    ('a -> ('b, 'e) result Lwt.t) -> ('a, 'e) result -> ('b, 'e) result Lwt.t

  val map_error : ('e -> 'f) -> ('a, 'e) result -> ('a, 'f) result

  (* NOTE: [map_error_e] is [bind_error] *)
  val map_error_e :
    ('e -> ('a, 'f) result) -> ('a, 'e) result -> ('a, 'f) result

  val map_error_s : ('e -> 'f Lwt.t) -> ('a, 'e) result -> ('a, 'f) result Lwt.t

  (* NOTE: [map_error_es] is [bind_error_s] *)
  val map_error_es :
    ('e -> ('a, 'f) result Lwt.t) -> ('a, 'e) result -> ('a, 'f) result Lwt.t

  val fold : ok:('a -> 'c) -> error:('e -> 'c) -> ('a, 'e) result -> 'c

  val iter : ('a -> unit) -> ('a, 'e) result -> unit

  val iter_s : ('a -> unit Lwt.t) -> ('a, 'e) result -> unit Lwt.t

  val iter_error : ('e -> unit) -> ('a, 'e) result -> unit

  val iter_error_s : ('e -> unit Lwt.t) -> ('a, 'e) result -> unit Lwt.t

  val is_ok : ('a, 'e) result -> bool

  val is_error : ('a, 'e) result -> bool

  val equal :
    ok:('a -> 'a -> bool) ->
    error:('e -> 'e -> bool) ->
    ('a, 'e) result ->
    ('a, 'e) result ->
    bool

  val compare :
    ok:('a -> 'a -> int) ->
    error:('e -> 'e -> int) ->
    ('a, 'e) result ->
    ('a, 'e) result ->
    int

  val to_option : ('a, 'e) result -> 'a option

  val of_option : error:'e -> 'a option -> ('a, 'e) result

  val to_list : ('a, 'e) result -> 'a list

  val to_seq : ('a, 'e) result -> 'a Stdlib.Seq.t
end